Jpn. Pat. Appln. KOKAI Publication No. 2008-96745 (Patent Document 1) discloses a lens group (light guiding lenses), through which the light emitted from a plurality of light emitting diodes (LEDs) is output. The light guiding lenses are formed close to each other and integral as one body, with a plurality of couplers, bent to a U-shape, interposed therebetween.
Since the couplers are formed integral as one body and made of the same transparent resin as the light guiding lenses, the light passing through one of adjacent light guiding lenses will be transmitted to the other light guiding lens via the corresponding coupler. If a great amount of light is transmitted via the coupler, part of the light may well be transmitted to a light output portion adjacent to a target one, with the result that selective emission through a desired one of light output portions cannot be realized.
To avoid this, in Patent Document 1, the couplers coupled to the lenses are bent to a U-shape in order to minimize the amount of light undesirably transmitted to a non-target light guiding lens via one of the couplers.
However, in Patent Document 1, the idea of bending the couplers to a U-shape cannot sufficiently realize selective emission through a desired one of light output portions, although the light passing through the couplers is suppressed. For instance, in Patent Document 1, since there is nothing between the light guiding lenses, light will be transmitted between adjacent light guiding lenses. In addition, since the distance between the light input portion of each light guiding lens to the adjacent coupler is relatively short, the light that has entered the light input portion of a target light guiding lens will easily be transmitted to the adjacent light guiding lens through the coupler located between these lenses.